How to read a file from installed folder c/c++ - c++

Question

I'm using Visual Studio and I have a code that uses several files and made an installer for it. Everything works fine if the user installs the program to the directory that is mentioned in the code (c:\games).
For example:
FILE *myfile;
if ((myfile = fopen("c:\\games\\heretics.txt", "r")) == NULL) {
printf("Cannot Open File heretics.txt\n"); return -1;
}
while ( (fgets(p, 256, myfile)) != NULL ) {
printf("%s",p);
}
fclose(myfile);
It stops working if the user installs it to any other directory. How to make the program read the files from any directory or what could be the solution for this?

Answer 1

If a "heretics.txt" file is in directory of your program (or somewhere near in directory tree) you can just write something like:
fopen("heretics.txt", "r") // to open file from current directory
fopen("..\\heretics.txt", "r") // to open file from parent directory
// and so on ;)
to use relative path instead of absolute path (as mentioned in comment above).

Answer 2

If you want to read files from the directory that the application's EXE file is in, you will need to determine that directory at run-time. Don't hard-code paths into your source code, or rely on the working directory!
To do that in Windows, you can call the GetModuleFileName function, which will return the fully-qualified path to the EXE file. Then you need to strip the EXE file name from the path (e.g. using PathRemoveFileSpec), to give you the directory.
#include <Windows.h>
#include <shlwapi.h>
#pragma comment(lib, "shlwapi.lib")
TCHAR szPath[MAX_PATH];
GetModuleFileName(NULL, szPath, MAX_PATH);
PathRemoveFileSpec(szPath);
You can then append your file name to the path like so:
PathAppend(szPath, TEXT("heretics.txt"));
And then you can pass szPath as the fully-qualified path to fopen or whatever function you're using to open the file.
But...
You should consider carefully whether the application's directory is the best place to store these files.
If either the application itself is going to write to the files (e.g., update them with new changes), or if the user might want to edit them, the application's directory is a terrible place. By default, applications get installed into the "Program Files" directory, for which users do not have edit privileges. Same thing with your example, at the root level of the disk.
Instead, you should save the files from one of the "Application Data" folders. You have the following choices:
FOLDERID_ProgramData (a global program data directory available to all users)
FOLDERID_LocalAppData (a per-user program data directory, non-roaming)
FOLDERID_RoamingAppData (a per-user program data directory, roaming)
Those magic names are the KNOWNFOLDERID constants that you pass to the SHGetKnownFolderPath function to retrieve the path to one of these folders. For example:
#include <Windows.h>
#include <ShlObj.h>
#pragma comment (lib, "shell32.lib")
// Retrieve the path.
PWSTR pszPath;
HRESULT hr = SHGetKnownFolderPath(&FOLDERID_ProgramData,
0, // no special options required
NULL, // no access token required
&pszPath);
// Copy it into a local string.
TCHAR szPath[MAX_PATH];
lstrcpy(szPath, pszPath);
// Free the memory allocated by the SHGetKnownFolderPath function,
// so you don't accidentally leak it!
CoTaskMemFree(pszPath);